# I'm stumped, whats the missing number

Discussion in 'After Hours Lounge (Off Topic)' started by Bill Griffith, Apr 1, 2003.

1. ### Bill Griffith Supporting Actor

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Find the missing number in the following sequence.

This problem was given on a 4rth grade math test.

1,5,10,15,25,50,?

I haven't been able to figure it out yet. Not only do you have to say the number but you have to say how you got it.

2. ### Lee L Supporting Actor

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That is a tough one. At first glance I thought 75 since for all the numbers in the series except the first a+b=c, b+c=d... 5+10+15, 10+15=25, 15+25=50, 25+50=75? but that darn 1 in there has me stumped. We should just eliminate that from consideration sice it doesn't fit the theory.

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4. ### MickeS Producer

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Those have to be some smart 4th graders.

/Mike

5. ### Jay H Producer

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Yeah, I was thinking the same thing, until I got to 15+25...

Jay

6. ### TimDoss Second Unit

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2.4 Understand the concept of percent(1%, 5%, 10%, 15%, 25%, 50%, 100%)

coincidence?

7. ### TimDoss Second Unit

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I like this one:

12, 6, 3, 5, ?

8. ### MickeS Producer

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So there is no logic, just a random set of numbers that was put down as an example of percentage numbers? That makes more sense... not.

/Mike

9. ### Dheiner Gazoo Supporter

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Um, when was the test dated?

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11. ### Graeme Clark Cinematographer

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I don't know about you, but we don't have 15 cent coins around here anyway.

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13. ### Bill Griffith Supporting Actor

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Houston fourth grade class, the test was given yesterday.

If the 50 is changed to a 40 it works out nicely at 65. So that was my guess, I think the teacher goofed.

I have a whole room of engineers trying to figure this thing out and no luck yet. We're gonna feel awfully stupid if there is an actual answer to this one.

14. ### Ricky Hustle Supporting Actor

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The answer is 100, although I'm surprised that question was aimed at 4th graders. My chart is way too sloppy and big to translate onto this page, but eventually patterns emerge when you relate all the numbers together.

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16. ### Bill Griffith Supporting Actor

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Rick - yeah, uh ok.

17. ### BrianW Cinematographer

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Artur, if your solution were correct, then subsequent numbers would be odd (and incremented by 2) forevermore. It may still be the correct solution, but without a second precedent for treatment of odd numbers, the problem amounts to a despicable fake-out since it suddenly changes the rules on the fourth number.

So I believe that something more consistent must be involved here.

18. ### Artur Meinild Screenwriter

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double post... now we don't need two copies of jack black's ass right after each other, do we?

19. ### ken thompson Second Unit

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4 is the missing number

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